Quantification of the distributions of gluten, starch and air bubbles in dough at different mixing stages by fluorescence fingerprint imaging

A method combining fluorescence fingerprint (FF) measurement with an imaging technique was developed to visualize the distributions of gluten and starch in dough. The fluorescence images of dough at the under-, optimum- and over-mixing stages were acquired in multiple excitation and emission wavelengths constructing the FF. This data containing the FF data of each pixel in the sample image was colored according to the similarity of the FF of each pixel and the FF of gluten or starch. Furthermore, the areas corresponding to air bubbles in the dough were masked in black. The resulting image, referred to as the FF pseudocolor image, showed the distributions of gluten and starch in the dough with the incorporated bubbles. Quantitative parameters concerning gluten and starch distributions and bubble area were extracted from the dough images at each mixing stage, showing the homogenization of gluten and starch and the incorporation of bubbles with mixing. This imaging method is suggested to have an advantage over conventional imaging methods since there is no need to preprocess the sample, and any constituent in the sample can be visualized as long as there is information about the FF of the pure target constituent.

► Fluorescence fingerprint (FF) measurement was combined with imaging technique.
► Distributions of gluten, starch and bubbles in dough were visualized.
► Gluten and starch distributions and bubble area were quantified.
► Gluten and starch distributions became homogeneous in the optimum-mixing stage.
► Bubble area increased in the over-mixing stage.